Global-scale Joint Body and Surface Wave Tomography with Vertical Transverse Isotropy in the Crust and Mantle

A series of global-scale seismic images of Earth's crust and mantle have been produced in recent years for seismic event monitoring applications (LLNL-G3D series, Simmons et al. 2011, 2012, and 2015). These models primarily focused on the prediction of body wave travel times for a suite of P and S body wave phases, allowing for more accurate event location estimates for events occurring anywhere in the world (Myers et al. 2015). We are currently incorporating global surface wave observations in the form of Love and Rayleigh dispersion relationships across a broad frequency range, while also fitting crustal, regional, and teleseismic body waves simultaneously. It is well-known that in order to simultaneously fit Love, Rayleigh, and body waves, terms representing radial anisotropy are required to account for the observed velocity of waves with differing propagation directions and particle motions. Therefore, we model vertical Vp, vertical Vs as well as 3 anisotropy parameters defined at each point to account for vertical transverse isotropy (VTI). We will present the development details of this newest model, which represents the next stage in a fully integrated Earth model capable of predicting a wider variety of seismic wave propagation characteristics for monitoring applications. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. LLNL-ABS-698621